Quantum Hall Effect in an Epitaxial Nitride Semiconductor/Superconductor Heterostructure*

The quantum Hall effect (QHE) is a paragon of topological protection in electronic states, exhibiting exceptional precision in resistance, while superconductivity allows exceptional precision in voltage due to flux quantization. To create seamless heterostructures of these two electronic phases is highly desirable for the discovery of new physics and use in quantum information science. To this end, we design an all-epitaxial superconductor/semiconductor nitride heterostructure, based on GaN two-dimensional electron gases (2DEGs) and superconducting NbN, using an industrial device process that is compatible with silicon and nitride semiconductor technology. The heterostructure is demonstrated to simultaneously exhibit the integer QHE in the GaN 2DEG and superconductivity in the NbN. Such a demonstration in an all-epitaxial nitride heterostructure is the first of its kind and paves the way for new quantum technologies.